package reivew;

/**
 * @author oldliu
 * @since 1.0
 */
public class ArrayMul {
    public static void main(String[] args) {
        int[]a=new int[20];
        for(int i=0;i<a.length;i++)
            a[i]=i+1;
        double sum=1;
        for(int i=0;i<a.length;i++){
            sum*=a[i];
        }
        System.out.println(sum);
    }
}
